ServiceLoader

findFirst

public Optional<S> findFirst ()

Load the first available service provider of this loader's service. This convenience method is equivalent to invoking the iterator() method and obtaining the first element. It therefore returns the first element from the provider cache if possible, it otherwise attempts to load and instantiate the first provider.

The following example loads the first available service provider. If no service providers are located then it uses a default implementation.

CodecFactory factory = ServiceLoader.load(CodecFactory.class)
                                        .findFirst()
                                        .orElse(DEFAULT_CODECSET_FACTORY);
 

iterator

public Iterator<S> iterator ()

Returns an iterator to lazily load and instantiate the available providers of this loader's service.

To achieve laziness the actual work of locating and instantiating providers is done by the iterator itself. Its hasNext and next methods can therefore throw a ServiceConfigurationError for any of the reasons specified in the Errors section above. To write robust code it is only necessary to catch ServiceConfigurationError when using the iterator. If an error is thrown then subsequent invocations of the iterator will make a best effort to locate and instantiate the next available provider, but in general such recovery cannot be guaranteed.

Caching: The iterator returned by this method first yields all of the elements of the provider cache, in the order that they were loaded. It then lazily loads and instantiates any remaining service providers, adding each one to the cache in turn. If this loader's provider caches are cleared by invoking the reload method then existing iterators for this service loader should be discarded. The hasNext and next methods of the iterator throw ConcurrentModificationException if used after the provider cache has been cleared.

The iterator returned by this method does not support removal. Invoking its remove method will cause an UnsupportedOperationException to be thrown.

load

public static ServiceLoader<S> load (Class<S> service)

Creates a new service loader for the given service type, using the current thread's context class loader.

An invocation of this convenience method of the form

ServiceLoader.load(service)
 

ServiceLoader.load(service, Thread.currentThread().getContextClassLoader())
 

load

public static ServiceLoader<S> load (Class<S> service, 
                ClassLoader loader)

Creates a new service loader for the given service. The service loader uses the given class loader as the starting point to locate service providers for the service.